This is the first of the EX (Export) models and was available from 1932 to 1936 according to Jim Dicks book. The pricker control works like a seesaw using the spring in the vapouriser and requires very little movement. I like the system and find it much easier to use than the twist and return method. It took me years to first see one of these little lone get hold of one. As the way things so often work, two weeks later I got another one.